There are many opinions about what causes this and how to fix it. First clean the carb, adjust valves if that applies, check springs on the throttle and the governor, drill out carb plugs and drill jets (at your own risk) or you can just choke it a touch and it goes away. So many choices so it's up to you. Also it's best to charge any battery before you install it in your car, even a new one. Alternators are not battery chargers. Thanks for watching.
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https://www.youtube.com/watch?v=4wNwmt4jRKM
The strips were so cheep, and I got to use some old power converters, that I just went for it. Works better than I thought it would. Two strips 16 feet long, two old wall warts, and some power all for $15.
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https://www.youtube.com/watch?v=z69z6dSckfU